1. Field of the Invention
This invention relates to the mass production of semiconductor devices, such as thyristors, and more particularly, to an apparatus for aligning and soldering pedestals or disks to the solderable ohmic contacts of semiconductor components.
2. Description of the Prior Art
It is generally known that semiconductor components can be produced starting with a diffused, i.e. exhibiting at least two zones of differing conductivity types, silicon wafer. The silicon wafer is divided into semiconductor chips by etching the wafer into a grid pattern. The individual semiconductor components are provided with solderable ohmic contacts (electrodes) and with layers of glass passivation, at least around the edge.
It is known (DT-OS 2,400,863) how to provide a pedestal or disk for connection to an external anodic terminal so that in the region of the mesa edge of the semiconductor component protected by the glass passivation, the solder spots necessary for the anode terminal and the pn-junction are kept well apart in this region. At the same time the pedestal, of course, acts as a current conductor and as a means of carrying off the heat generated. In the known case the pedestal next to the anode electrode is aligned with a cooling fin comb. This cooling fin comb is located on the side away from the electrode and is pre-attached by thermo-compression. On the other side of the semiconductor chip is laid a double comb made of two combs of different sheet thicknesses. The double comb is provided with contact legs and additional contact vanes. The contact leg acts as a control electrode terminal, while the contact vane acts as an emitter electrode terminal. Cooling fins, contact legs and contact vanes are soldered to their respective electrodes in one process. In the known method for producing semiconductor chips, the silicon wafer has already been divided into individual semiconductor chips before electrode pedestals are attached. However, it is more economical in the production process to carry out as many operations as possible on the undivided wafer.